AndroidでSQLiteのテーブルからすべてのレコードを削除する方法？
私のアプリには2つのボタンがあり、最初のボタンはユーザー入力のレコードを削除するためのもので、2番目のボタンはすべてのレコードを削除するためのものです。しかし、私がデータを削除したいとき、それはメッセージを示します
「あなたのアプリケーションは強制的に停止されました」。
私のコードをチェックして、私に何か提案をください。
public void deleteAll()
{
//SQLiteDatabase db = this.getWritableDatabase();
// db.delete(TABLE_NAME,null,null);
//db.execSQL("delete * from"+ TABLE_NAME);
db.execSQL("TRUNCATE table" + TABLE_NAME);
db.close();
}
そして
public void delete(String id)
{
String[] args={id};
getWritableDatabase().delete("texts", "_ID=?", args);
}
しかし、それは以下のLog catエラーを示しています。
03-07 15:57:07.143: ERROR/AndroidRuntime(287): Uncaught handler: thread main exiting due to uncaught exception
03-07 15:57:07.153: ERROR/AndroidRuntime(287): Java.lang.NullPointerException
03-07 15:57:07.153: ERROR/AndroidRuntime(287): at com.example.MySQLiteHelper.delete(MySQLiteHelper.Java:163)
03-07 15:57:07.153: ERROR/AndroidRuntime(287): at com.example.Settings$4.onClick(Settings.Java:94)
-07 15:57:07.153: ERROR/AndroidRuntime(287): at com.Android.internal.app.AlertController$ButtonHandler.handleMessage(AlertController.Java:158)
03-07 15:57:07.153: ERROR/AndroidRuntime(287): at Android.os.Handler.dispatchMessage(Handler.Java:99)
03-07 15:57:07.153: ERROR/AndroidRuntime(287): at Android.os.Looper.loop(Looper.Java:123)
03-07 15:57:07.153: ERROR/AndroidRuntime(287): at Android.app.ActivityThread.main(ActivityThread.Java:4203)
03-07 15:57:07.153: ERROR/AndroidRuntime(287): at Java.lang.reflect.Method.invokeNative(Native Method)
03-07 15:57:07.153: ERROR/AndroidRuntime(287): at Java.lang.reflect.Method.invoke(Method.Java:521)
03-07 15:57:07.153: ERROR/AndroidRuntime(287): at com.Android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.Java:791)
03-07 15:57:07.153: ERROR/AndroidRuntime(287): at com.Android.internal.os.ZygoteInit.main(ZygoteInit.Java:549)
03-07 15:57:07.153: ERROR/AndroidRuntime(287): at dalvik.system.NativeStart.main(Native Method)
あなたはスペースを逃しました：db.execSQL("delete * from " + TABLE_NAME);
また、*を含める必要さえない、正しいクエリは次のとおりです。
db.execSQL("delete from "+ TABLE_NAME);
db.delete(TABLE_NAME, null, null);
関数に削除された行の数を返す場合は、
db.delete(TABLE_NAME, "1", null);
SQLiteDatabaseのドキュメントから 削除 メソッド：
すべての行を削除してカウントを取得するには、whereClauseとして "1"を渡します。
テーブル内のすべての行を削除するには、次のようにします。
db.delete(TABLE_NAME, null, null);
SQLiteはTRUNCATEコマンドをサポートしていません。前の行で試したものを使用する必要があります。
DELETE FROM `TABLE_NAME`;
P.Sクエリごとに新しいデータベースを作成するのではなく、特定のデータベースへのすべてのクエリに対してデータベース接続の同じインスタンスを使用することで、プログラムを最適化できます。
"execute"関数を使う必要はありません。次のコードが私のために働きました:::
db.delete(TABLE_NAME,null,null);
db.close();
SQLiteDatabase db = this.getWritableDatabase();
db.execSQL("DELETE FROM tablename"); //delete all rows in a table
db.close();
この仕事は私のために:)
このコードを試して、テーブルからすべてのデータを削除してください。
String selectQuery = "DELETE FROM table_name ";
Cursor cursor = data1.getReadableDatabase().rawQuery(selectQuery, null);
私はこのクラスを使用してデータベースを処理します。将来的に役立つことを願っています。
ハッピーコーディング.
public class Database {
private static class DBHelper extends SQLiteOpenHelper {
/**
* Database name
*/
private static final String DB_NAME = "db_name";
/**
* Table Names
*/
public static final String TABLE_CART = "DB_CART";
/**
* Cart Table Columns
*/
public static final String CART_ID_PK = "_id";// Primary key
public static final String CART_DISH_NAME = "dish_name";
public static final String CART_DISH_ID = "menu_item_id";
public static final String CART_DISH_QTY = "dish_qty";
public static final String CART_DISH_PRICE = "dish_price";
/**
* String to create reservation tabs table
*/
private final String CREATE_TABLE_CART = "CREATE TABLE IF NOT EXISTS "
+ TABLE_CART + " ( "
+ CART_ID_PK + " INTEGER PRIMARY KEY, "
+ CART_DISH_NAME + " TEXT , "
+ CART_DISH_ID + " TEXT , "
+ CART_DISH_QTY + " TEXT , "
+ CART_DISH_PRICE + " TEXT);";
public DBHelper(Context context) {
super(context, DB_NAME, null, 2);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL(CREATE_TABLE_CART);
}
@Override
public void onUpgrade(SQLiteDatabase db, int arg1, int arg2) {
db.execSQL("DROP TABLE IF EXISTS " + CREATE_TABLE_CART);
onCreate(db);
}
}
/**
* CART handler
*/
public static class Cart {
/**
* Check if Cart is available or not
*
* @param context
* @return
*/
public static boolean isCartAvailable(Context context) {
DBHelper dbHelper = new DBHelper(context);
SQLiteDatabase db = dbHelper.getReadableDatabase();
boolean exists = false;
try {
String query = "SELECT * FROM " + DBHelper.TABLE_CART;
Cursor cursor = db.rawQuery(query, null);
exists = (cursor.getCount() > 0);
cursor.close();
db.close();
} catch (SQLiteException e) {
db.close();
}
return exists;
}
/**
* Insert values in cart table
*
* @param context
* @param dishName
* @param dishPrice
* @param dishQty
* @return
*/
public static boolean insertItem(Context context, String itemId, String dishName, String dishPrice, String dishQty) {
DBHelper dbHelper = new DBHelper(context);
SQLiteDatabase db = dbHelper.getWritableDatabase();
ContentValues values = new ContentValues();
values.put(DBHelper.CART_DISH_ID, "" + itemId);
values.put(DBHelper.CART_DISH_NAME, "" + dishName);
values.put(DBHelper.CART_DISH_PRICE, "" + dishPrice);
values.put(DBHelper.CART_DISH_QTY, "" + dishQty);
try {
db.insert(DBHelper.TABLE_CART, null, values);
db.close();
return true;
} catch (SQLiteException e) {
db.close();
return false;
}
}
/**
* Check for specific record by name
*
* @param context
* @param dishName
* @return
*/
public static boolean isItemAvailable(Context context, String dishName) {
DBHelper dbHelper = new DBHelper(context);
SQLiteDatabase db = dbHelper.getReadableDatabase();
boolean exists = false;
String query = "SELECT * FROM " + DBHelper.TABLE_CART + " WHERE "
+ DBHelper.CART_DISH_NAME + " = '" + String.valueOf(dishName) + "'";
try {
Cursor cursor = db.rawQuery(query, null);
exists = (cursor.getCount() > 0);
cursor.close();
} catch (SQLiteException e) {
e.printStackTrace();
db.close();
}
return exists;
}
/**
* Update cart item by item name
*
* @param context
* @param dishName
* @param dishPrice
* @param dishQty
* @return
*/
public static boolean updateItem(Context context, String itemId, String dishName, String dishPrice, String dishQty) {
DBHelper dbHelper = new DBHelper(context);
SQLiteDatabase db = dbHelper.getWritableDatabase();
ContentValues values = new ContentValues();
values.put(DBHelper.CART_DISH_ID, itemId);
values.put(DBHelper.CART_DISH_NAME, dishName);
values.put(DBHelper.CART_DISH_PRICE, dishPrice);
values.put(DBHelper.CART_DISH_QTY, dishQty);
try {
String[] args = new String[]{dishName};
db.update(DBHelper.TABLE_CART, values, DBHelper.CART_DISH_NAME + "=?", args);
db.close();
return true;
} catch (SQLiteException e) {
db.close();
return false;
}
}
/**
* Get cart list
*
* @param context
* @return
*/
public static ArrayList<CartModel> getCartList(Context context) {
DBHelper dbHelper = new DBHelper(context);
SQLiteDatabase db = dbHelper.getReadableDatabase();
ArrayList<CartModel> cartList = new ArrayList<>();
try {
String query = "SELECT * FROM " + DBHelper.TABLE_CART + ";";
Cursor cursor = db.rawQuery(query, null);
for (cursor.moveToFirst(); !cursor.isAfterLast(); cursor.moveToNext()) {
cartList.add(new CartModel(
cursor.getString(cursor.getColumnIndex(DBHelper.CART_DISH_ID)),
cursor.getString(cursor.getColumnIndex(DBHelper.CART_DISH_NAME)),
cursor.getString(cursor.getColumnIndex(DBHelper.CART_DISH_QTY)),
Integer.parseInt(cursor.getString(cursor.getColumnIndex(DBHelper.CART_DISH_PRICE)))
));
}
db.close();
} catch (SQLiteException e) {
db.close();
}
return cartList;
}
/**
* Get total amount of cart items
*
* @param context
* @return
*/
public static String getTotalAmount(Context context) {
DBHelper dbHelper = new DBHelper(context);
SQLiteDatabase db = dbHelper.getReadableDatabase();
double totalAmount = 0.0;
try {
String query = "SELECT * FROM " + DBHelper.TABLE_CART + ";";
Cursor cursor = db.rawQuery(query, null);
for (cursor.moveToFirst(); !cursor.isAfterLast(); cursor.moveToNext()) {
totalAmount = totalAmount + Double.parseDouble(cursor.getString(cursor.getColumnIndex(DBHelper.CART_DISH_PRICE))) *
Double.parseDouble(cursor.getString(cursor.getColumnIndex(DBHelper.CART_DISH_QTY)));
}
db.close();
} catch (SQLiteException e) {
db.close();
}
if (totalAmount == 0.0)
return "";
else
return "" + totalAmount;
}
/**
* Get item quantity
*
* @param context
* @param dishName
* @return
*/
public static String getItemQty(Context context, String dishName) {
DBHelper dbHelper = new DBHelper(context);
SQLiteDatabase db = dbHelper.getReadableDatabase();
Cursor cursor = null;
String query = "SELECT * FROM " + DBHelper.TABLE_CART + " WHERE " + DBHelper.CART_DISH_NAME + " = '" + dishName + "';";
String quantity = "0";
try {
cursor = db.rawQuery(query, null);
if (cursor.getCount() > 0) {
cursor.moveToFirst();
quantity = cursor.getString(cursor
.getColumnIndex(DBHelper.CART_DISH_QTY));
return quantity;
}
} catch (SQLiteException e) {
e.printStackTrace();
}
return quantity;
}
/**
* Delete cart item by name
*
* @param context
* @param dishName
*/
public static void deleteCartItem(Context context, String dishName) {
DBHelper dbHelper = new DBHelper(context);
SQLiteDatabase db = dbHelper.getReadableDatabase();
try {
String[] args = new String[]{dishName};
db.delete(DBHelper.TABLE_CART, DBHelper.CART_DISH_NAME + "=?", args);
db.close();
} catch (SQLiteException e) {
db.close();
e.printStackTrace();
}
}
}//End of cart class
/**
* Delete database table
*
* @param context
*/
public static void deleteCart(Context context) {
DBHelper dbHelper = new DBHelper(context);
SQLiteDatabase db = dbHelper.getReadableDatabase();
try {
db.execSQL("DELETE FROM " + DBHelper.TABLE_CART);
} catch (SQLiteException e) {
e.printStackTrace();
}
}
}
使用法
if(Database.Cart.isCartAvailable(context)){
Database.deleteCart(context);
}
書くだけ
SQLiteDatabase db = this.getWritableDatabase();
db.execSQL("delete from "+TableName);
または
db.delete(tablename,null,null);
最後の2つのnullパラメータでSqliteの削除関数を使用します。
db.delete(TABLE_NAME,null,null)
//Delete all records of table
db.execSQL("DELETE FROM " + TABLE_NAME);
//Reset the auto_increment primary key if you needed
db.execSQL("UPDATE SQLITE_SEQUENCE SET SEQ=0 WHERE NAME=" + TABLE_NAME);
//For go back free space by shrinking sqlite file
db.execSQL("VACUUM");
getContentResolver().delete(DB.TableName.CONTENT_URI, null, null);
これは私のために働くでしょう。 execSQLとrawQueryの違いはここにあります。 rawQueryは検索ケースで最も使用され、execSQLは主に適用操作で使用されます。
// truncate the table
ArrayList<HashMap<String, String>> getDatabaseName1(String sr) {
SQLiteDatabase sqLiteDatabase=this.getWritableDatabase();
sqLiteDatabase.execSQL("delete from Hotel");
sqLiteDatabase.close();
return null;
}
役に立つ場合があります
public boolean deleteAllFood() {
SQLiteDatabase db = dbHelper.getReadableDatabase();
int affectedRows = db.delete(DBHelper.TABLE_NAME_FOOD, null, null);
return affectedRows > 0;
}
public class DBProgram {
private static DBProgram INSTANCE;
private Context context;
private DBHelper dbHelper;
private DBProgram(Context context) {
// burda bu methodu kullanan activity ile eileştiriyoruz
this.dbHelper = new DBHelper(context);
}
public static synchronized DBProgram getInstance(Context context) {
if (INSTANCE == null) {
INSTANCE = new DBProgram(context);
}
return INSTANCE;
}
//**********************************************
public boolean updateById(ProgramModel program) {
SQLiteDatabase database = dbHelper.getWritableDatabase();
ContentValues contentValues = new ContentValues();
contentValues.put(DBHelper.COLUM_NAME_P, program.getProgName());
contentValues.put(DBHelper.COLUM_DAY_P, program.getDay());
contentValues.put(DBHelper.COLUMN_WEIGHT_P, program.getWeight());
contentValues.put(DBHelper.COLUMN_SET_P, program.getSet());
contentValues.put(DBHelper.COLUMN_REPETITION_P, program.getRepetition());
int affectedRows = database.update(DBHelper.TABLE_NAME_PROGRAM, contentValues, "PROG_ID_P = ?", new String[]{String.valueOf(program.getId())});
return affectedRows > 0;
}
//**********************************************
//**********************************************
// TODO
public boolean deleteProgramById(int id) {
SQLiteDatabase database = dbHelper.getReadableDatabase();
int affectedRows = database.delete(DBHelper.TABLE_NAME_PROGRAM, DBHelper.COLUMN_ID_P + "= ?", new String[]{String.valueOf(id)});
// return bize etkilenen sıra sayısınıını temsil eder
return affectedRows > 0;
}
//**********************************************
//***************************************************
public boolean deleteProgramByName(String progName) {
SQLiteDatabase database = dbHelper.getReadableDatabase();
final String whereClause = DBHelper.COLUM_NAME_P + "=?";
final String whereArgs[] = {progName};
int affectedRows = database.delete(DBHelper.TABLE_NAME_PROGRAM, whereClause, whereArgs);
return affectedRows > 0;
}
//***************************************************
//************************************** get Meal
// TODO WEB Get All Meals
public List<ProgramModel> getAllProgram(String name) {
List<ProgramModel> foodList = new ArrayList<>();
ProgramModel food;
SQLiteDatabase database = dbHelper.getReadableDatabase();
final String kolonlar[] = {DBHelper.COLUMN_ID_P,
DBHelper.COLUM_NAME_P,
DBHelper.COLUM_DAY_P,
DBHelper.COLUMN_WEIGHT_P,
DBHelper.COLUMN_SET_P,
DBHelper.COLUMN_REPETITION_P};
final String whereClause = DBHelper.COLUM_DAY_P + "=?";
final String whereArgs[] = {name};
Cursor cursor = database.query(DBHelper.TABLE_NAME_PROGRAM, kolonlar, whereClause, whereArgs, null, null, null);
while (cursor.moveToNext()) {
food = new ProgramModel();
food.setId(cursor.getInt(cursor.getColumnIndex(DBHelper.COLUMN_ID_P)));
food.setProgName(cursor.getString(cursor.getColumnIndex(DBHelper.COLUM_NAME_P)));
food.setDay(cursor.getString(cursor.getColumnIndex(DBHelper.COLUM_DAY_P)));
food.setWeight(cursor.getInt(cursor.getColumnIndex(DBHelper.COLUMN_WEIGHT_P)));
food.setSet(cursor.getInt(cursor.getColumnIndex(DBHelper.COLUMN_SET_P)));
food.setRepetition(cursor.getInt(cursor.getColumnIndex(DBHelper.COLUMN_REPETITION_P)));
foodList.add(food);
}
database.close();
cursor.close();
return foodList;
}
//**************************************
//**************************************insert FOOD
//TODO LOCAL insert Foods
public boolean insertProgram(ProgramModel favorite) {
boolean result = false;
ContentValues contentValues = new ContentValues();
contentValues.put(DBHelper.COLUM_NAME_P, favorite.getProgName());
contentValues.put(DBHelper.COLUM_DAY_P, favorite.getDay());
contentValues.put(DBHelper.COLUMN_WEIGHT_P, favorite.getWeight());
contentValues.put(DBHelper.COLUMN_SET_P, favorite.getSet());
contentValues.put(DBHelper.COLUMN_REPETITION_P, favorite.getRepetition());
SQLiteDatabase database = dbHelper.getWritableDatabase();
long id = database.insert(DBHelper.TABLE_NAME_PROGRAM, null, contentValues);
if (id != 1) {
result = true;
}
database.close();
return result;
}
//***************************************************
// ******************************* SQLITE HELPER CLASS ******************
private class DBHelper extends SQLiteOpenHelper {
private final Context context;
private static final String DATABASE_NAME = "PROGRAM_INFO";
private static final String TABLE_NAME_PROGRAM = "PROGRAM";
private static final int DATABASE_VERSION = 2;
// FOOD
private static final String COLUMN_ID_P = "PROG_ID_P";
private static final String COLUM_NAME_P = "PROG_NAME_P";
private static final String COLUM_DAY_P = "PROG_DAY_P";
private static final String COLUMN_WEIGHT_P = "PROG_WEIGHT_P";
private static final String COLUMN_SET_P = "PROG_SET_P";
private static final String COLUMN_REPETITION_P = "PROG_REPETITION_P";
private final String CREATE_TABLE_PROGRAM = "CREATE TABLE " + TABLE_NAME_PROGRAM +
" (" + COLUMN_ID_P + " INTEGER PRIMARY KEY AUTOINCREMENT, "
+ COLUM_NAME_P + " TEXT, "
+ COLUM_DAY_P + " TEXT, "
+ COLUMN_WEIGHT_P + " INTEGER, "
+ COLUMN_SET_P + " INTEGER, "
+ COLUMN_REPETITION_P + " INTEGER)";
private static final String DROP_TABLE_PROGRAM = "DROP TABLE IF EXIST " + TABLE_NAME_PROGRAM;
public DBHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
this.context = context;
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL(CREATE_TABLE_PROGRAM);
Util.showMessage(context, "Database Created");
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL(DROP_TABLE_PROGRAM);
Util.showMessage(context, "Database Upgrated");
onCreate(db);
}
@Override
public void onDowngrade(SQLiteDatabase db, int oldVersion, int newVersion) {
super.onDowngrade(db, oldVersion, newVersion);
}
}
}
この方法は、データベースからすべてのデータを遅らせます
public void deleteAll()
{
SQLiteDatabase db = this.getWritableDatabase();
db.execSQL("delete from "+ TABLE_NAME);
db.close();
}